Wednesday, July 4, 2018

Season 12 superfinal, games 75-82

After 82 games Stockfish leads 22-7 with 53 draws. The draw rate continues to be low, now at 64.6%. Stockfish adds two more wins. It has a 15 game lead with 18 games left, soon to be declared the winner of the match.

Game 38.1 started with Stockfish down a knight for two pawns and Komodo's king in the center after moving forward. Stockfish created a central passer, the black king walked to the queen side for safety. Stockfish also had the bishop pair advantage.

Evals increased very slowly. The white passer was the center of attention for a while, then through a series of exchanges only RBB vs RRN were left on move 30. Komodo captured the central passer but Stockfish was two pawns up, and the bishops were stronger in an open position.

Stockfish concentrated its efforts on the king side where it had a pawn majority. It managed to create a connected pair of passers and captured another pawn. The g pawn moved forward alone and reached the 6th rank, and the LS bishop kept all the white pawns protected.

Komodo's defense collapsed, it was forced to lose a rook for a bishop and Stockfish with 3 pawns up was winning in a RB vs RN position.

In the reverse game 38.2 Stockfish kept its king in the center, and it was Komodo that gave a bishop for a knight. After a series of exchanges Stockfish got rid of the passer and only RRN vs RRB were left on move 24. Komodo was a pawn up but evals fell quickly to 0. The engines traded pawns until the game was adjudicated a draw. What a contrast to the previous game.

The black queen captured two pawns early in game 39.1 opening the white queen side. Komodo kept its king in the center uncastled. Evals started to increase as Stockfish drove the black queen away. Then Stockfish trapped a knight in the corner and gave a third pawn to weaken the black king side. Stockfish's eval jumped over 1, Komodo thought long to evaluate its situation.

There were many black pieces on the king side, Stockfish sacrificed a knight to open the queen side. Komodo's king was in real danger, it exchanged rooks and gave a bishop back in an attempt to find safety for its king and to untangle its pieces on the king side.

Stockfish put the attack on the black king on hold and created a queen side passer. The black queen finally found a way out of the corner, it tried to attack the white king but couldn't achieve much on its own. Stockfish won a rook for a bishop and prepared a protected corridor for its passer.

Stockfish shifted again to attack the black king. It traded R for BN to reach a QBN vs QN position, the game was adjudicated a few moves later.

In the reverse game 39.2 Komodo drove the black queen away, this time Stockfish prepared a safe place for it on the queen side. This allowed Stockfish to castle safely, evals favored black. Komodo won a rook for a bishop and pushed a passer in the center. Stockfish stopped the passer and exchanged queens, with RRN vs RBN remaining on move 35. Evals dropped to 0 as Stockfish blocked the open files effectively, the game ended in a draw.

In game 40.1 the engines castled in opposite directions, Komodo castling long. Stockfish pushed pawns on the queen side, weakening the black king. Komodo cleared most of its king side pawns, and it had a supported passer in the center. The engines shuffled for a while and then through a series of exchanges the game reached a RB vs RN position. The game ended in a tablebase draw. In the reverse game Stockfish went a pawn up and did not castle its king. Komodo gave a second pawn and opened a file in the center, it prevented black from castling long with its rook and queen. Stockfish castled short, its king very exposed with the center and king side open. On move 40 only QRR vs QRR remained, the engines gradually traded pawns and then reduced to a drawn rook ending. Komodo refused to lower its eval, the game went on another 50 moves.

Stockfish kept its king uncastled in game 41.1. The engines exchanged pawns on the queen side, the white king walked to the king side and trapped a rook in the corner. The engines exchanged pieces, on move 35 only QRR vs QRR remained. Stockfish freed its trapped rook, the engines exchanged a pair of rooks before the game was adjudicated a draw. In game 41.2 both engines castled, there were many early exchanges and only RBN vs RNN remained on move 21. The game reached a drawn rook ending.